Devoured By Gluttony by Wendy Cheairs

One of the youngest sons of a demon on a mission to infect Earth with all the Seven Deadly Sin, Zion Lee got stuck with Gluttony. As a Sin-Eater, he has enough problems eating and purging the sins of others, and now he had one he can’t get rid of, neither can anyone else. Only rumors swirl about ways to rid one’s self of a sin gifted by his demonic biological father. Since that day, he has become the eater of everything, sins, wealth, food, and everything in between.
Once the rumor of a curse-breaker reaches him in his native Singapore, he hires tracker Harry Watson, not expecting a kick-ass woman who knows how to find anything but already brings trouble in her wake. Between the two of them, they will find themselves on a journey across the planet amongst the supernatural and mundane world looking for a curse for one of the Deadly Sins. If the curse can be broken, Zion can save himself and his other cursed half-brothers, each with a different sin.